US4710731A - Planar type thickness shear mode quartz oscillator - Google Patents

Planar type thickness shear mode quartz oscillator Download PDF

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Publication number
US4710731A
US4710731A US06/885,931 US88593186A US4710731A US 4710731 A US4710731 A US 4710731A US 88593186 A US88593186 A US 88593186A US 4710731 A US4710731 A US 4710731A
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United States
Prior art keywords
resonator
oscillation
quartz
quartz resonator
thickness
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US06/885,931
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Mitsuyuki Sugita
Isamu Hoshino
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Seiko Precision Inc
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Seikosha KK
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02157—Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02062—Details relating to the vibration mode
    • H03H9/0207—Details relating to the vibration mode the vibration mode being harmonic
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
    • H03K3/027—Generators characterised by the type of circuit or by the means used for producing pulses by the use of logic circuits, with internal or external positive feedback
    • H03K3/03—Astable circuits
    • H03K3/0307—Stabilisation of output, e.g. using crystal

Definitions

  • This invention relates to planar type thickness shear mode quartz resonators or vibrators or oscillators such as AT-cut quartz resonators and more particularly to quartz resonators designed to oscillate in the third overtone.
  • Oscillation of a quartz oscillator is determined by the difference between the negative resistance of an oscillation circuit and the crystal impedance of the quartz oscillator, and the quartz oscillator oscillates in an oscillation mode in which the difference is greatest.
  • the negative resistance of an oscillation circuit tends to decrease in proportion as the frequency becomes high. In other words, the negative resistance decreases in proportion as the ratio D/T increases.
  • the characteristic curve of negative resistance of an oscillation circuit varies according to the IC (integrated circuit) used in the oscillation circuit, and the impedance of a quartz oscillator changes with the diameter and other factors.
  • the aforementioned relation exists fundamentally and the proportion D/T is usually designed within the range from 50 to 100 so as to get stable oscillation in fundamental tone.
  • Some conventional planar type quartz oscillators are driven in third overtone, but in such case, oscillation circuits are provided with tuning circuits composed of coils (L) and condensers (C).
  • the present invention provides a planar type thickness shear mode quartz oscillator to be operated by an oscillation circuit without a L, C (coils, condensers) tuning circuit in which the ratio between the diameter and the thickness of the oscillator is so designed as to perform stable oscillation in third overtone.
  • FIG. 1 is a graph showing the relationship between the proportion D/T of a quartz resonator or oscillator and the difference between negative resistance of an oscillation circuit and the impedance of the quartz resonator in each oscillation mode,
  • FIG. 2 is a plan view of a quartz resonator
  • FIG. 3 is an elevational view of the quartz resonator of FIG. 2,
  • FIG. 4 is an oscillation circuit which is not provided with a L, C (coils, condensers) tuning circuit,
  • FIG. 5 is a graph showing the relationship between frequency and negative resistance of the oscillation circuit
  • FIG. 6 is a graph showing the relationship between the proportion D/T of the quartz resonator or oscillator and crystal impedance (CI) in each oscillation mode,
  • FIG. 7 is a graph showing the relationship between the proportion D/T and negative resistance in fundamental tone
  • FIG. 8 is a graph showing the relationship between the proportion D/T and the negative resistance in third overtone
  • FIG. 9 is a graph showing the relationship between the proportion D/T and the negative resistance in fifth overtone.
  • the outer periphery of the resonator or oscillator is trimmed just a little (see FIG. 2) to lower impedance in overtone oscillations.
  • FIG. 4 is an oscillation circuit which is constructed without a L, C (coils, condensers) tuning circuit.
  • of the oscillation circuit and the frequency F(MHZ) of the oscillator follows a curve as shown in FIG. 5.
  • the shape of the curve varies a little according to the IC (integrated circuit) employed in the oscillation circuit, but each curve shows a similar declining curve.
  • the oscillation circuit can be composed of a small number of parts since it does not require a L, C (coils, condensers) tuning circuit, so the oscillation circuit can be made small. Since the quartz oscillator according to the present invention oscillates in third overtone, motional capacitance (Cm) can be made low and the influence of stray capacitance can be made small. Further, the quality factor Q can be made large, and the oscillator performs high stable oscillation with excellent aging characteristics. Furthermore, the quartz oscillator according to our present invention can be made thick as compared to the conventional quartz oscillators, and it is excellent in shock resistance.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

A planar type thickness shear mode quartz resonator which can be operated by an oscillation circuit free of any coils or condensers in the tuning circuit and in which the ratio between the diameter and the thickness of the resonator is so designed as to yield stable oscillation in the third overtone. The difference between the negative resistance of the oscillation circuit and the crystal impedance of the quartz resonator is greater in the third overtone than the difference in other oscillation modes.

Description

BACKGROUND OF THE INVENTION
This invention relates to planar type thickness shear mode quartz resonators or vibrators or oscillators such as AT-cut quartz resonators and more particularly to quartz resonators designed to oscillate in the third overtone.
Conventionally, in planar type quartz resonators or oscillators among thickness shear mode quartz oscillators, usually the proportions of diameters (D) and thicknesses (T) are so designed to oscillate the oscillators in fundamental tones. Commonly the proportion is within the range from D/T=50 to D/T=100. The reason is as follows. Oscillation of a quartz oscillator is determined by the difference between the negative resistance of an oscillation circuit and the crystal impedance of the quartz oscillator, and the quartz oscillator oscillates in an oscillation mode in which the difference is greatest. The negative resistance of an oscillation circuit tends to decrease in proportion as the frequency becomes high. In other words, the negative resistance decreases in proportion as the ratio D/T increases. Whereas the impedance of a quartz oscillator shows a sharp decline curve with respect to the proportion D/T, and impedance in fundamental tone becomes lowest among impedances in all oscillation modes near or above D/T=45. The characteristic curve of negative resistance of an oscillation circuit varies according to the IC (integrated circuit) used in the oscillation circuit, and the impedance of a quartz oscillator changes with the diameter and other factors. The aforementioned relation, however, exists fundamentally and the proportion D/T is usually designed within the range from 50 to 100 so as to get stable oscillation in fundamental tone. Some conventional planar type quartz oscillators are driven in third overtone, but in such case, oscillation circuits are provided with tuning circuits composed of coils (L) and condensers (C).
In the prior art, as described above, very thin quartz plates of D/T=50˜100 are employed and such quartz oscillators are subjected to the influence of supporting means, and it has been difficult to realize high, stable oscillations due to the decrease in the quality factor (Q). Further, the thickness of the quartz oscillators is so thin that they are low in shock resistance and apt to break. Further, in an oscillation device which is provided with a tuning circuit with L (coils) and C (condensers) for getting third overtone, it is inevitable that the device must be large due to the tuning circuit, especially the coil (L), and the structure becomes complex with the increased number of parts.
The present invention provides a planar type thickness shear mode quartz oscillator to be operated by an oscillation circuit without a L, C (coils, condensers) tuning circuit in which the ratio between the diameter and the thickness of the oscillator is so designed as to perform stable oscillation in third overtone.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings show an embodiment of the present invention in which,
FIG. 1 is a graph showing the relationship between the proportion D/T of a quartz resonator or oscillator and the difference between negative resistance of an oscillation circuit and the impedance of the quartz resonator in each oscillation mode,
FIG. 2 is a plan view of a quartz resonator,
FIG. 3 is an elevational view of the quartz resonator of FIG. 2,
FIG. 4 is an oscillation circuit which is not provided with a L, C (coils, condensers) tuning circuit,
FIG. 5 is a graph showing the relationship between frequency and negative resistance of the oscillation circuit,
FIG. 6 is a graph showing the relationship between the proportion D/T of the quartz resonator or oscillator and crystal impedance (CI) in each oscillation mode,
FIG. 7 is a graph showing the relationship between the proportion D/T and negative resistance in fundamental tone,
FIG. 8 is a graph showing the relationship between the proportion D/T and the negative resistance in third overtone,
FIG. 9 is a graph showing the relationship between the proportion D/T and the negative resistance in fifth overtone.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 2 and 3, a disc type AT cut, thickness shear mode quartz oscillator is prepared, in which D designates diameter and T designates thickness and in this case D=6 mm. The outer periphery of the resonator or oscillator is trimmed just a little (see FIG. 2) to lower impedance in overtone oscillations. FIG. 4 is an oscillation circuit which is constructed without a L, C (coils, condensers) tuning circuit. The relation between the negative resistance |R| of the oscillation circuit and the frequency F(MHZ) of the oscillator follows a curve as shown in FIG. 5. The shape of the curve varies a little according to the IC (integrated circuit) employed in the oscillation circuit, but each curve shows a similar declining curve.
In the case where the diameter of the quartz oscillator is 6 mm, the relation between the proportion D/T (diameter to thickness) and crystal impedance (CI) in respective oscillation modes is shown in FIG. 6. A proportional relationship exists between the thickness T of the quartz oscillator and the frequency F(MHZ) in the fundamental tone of the quartz oscillator. The relationship is provided by the following equation:
F(MHZ)=Kf/T (mm)
(Kf=1.670, approximately).
From the above equation and FIGS. 5 and 6, the relationship between the proportion D/T and crystal impedance (CI) and negative resistance |R| in different frequency modes are respectively shown in FIGS. 7, 8 and 9. The difference between the negative resistance |R| of the circuit and the impedance (CI) of the quartz oscillator in each oscillation mode can be calculated in each of FIGS. 7, 8 or 9, and such difference is indicated graphically in FIG. 1. From FIG. 1 the difference in third overtone is greatest between point A and point B wherein the quartz oscillator oscillates in third overtone, and we can obtain an inequality, 10<D/T<24. Practically speaking the third overtone oscillation is unstable near D/T=10 and D/T=24, and a stable third overtone oscillator can be obtained by determining and proportioning D/T avoiding such unstable regions.
According to the present invention, the oscillation circuit can be composed of a small number of parts since it does not require a L, C (coils, condensers) tuning circuit, so the oscillation circuit can be made small. Since the quartz oscillator according to the present invention oscillates in third overtone, motional capacitance (Cm) can be made low and the influence of stray capacitance can be made small. Further, the quality factor Q can be made large, and the oscillator performs high stable oscillation with excellent aging characteristics. Furthermore, the quartz oscillator according to our present invention can be made thick as compared to the conventional quartz oscillators, and it is excellent in shock resistance.

Claims (10)

What is claimed is:
1. An oscillator comprising a planar type thickness shear mode quartz resonator connected to a negative resistance oscillation circuit in which the proportion between the diameter and the thickness of the quartz resonator is so designed that the difference between the impedance of the quartz resonator and the negative resistance of the oscillation circuit is greater in the third overtone than in other oscillation modes.
2. The quartz resonator of claim 1 in which the proportion between the diameter and the thickness of the resonator is greater than 10 and less then 24.
3. The quartz resonator of claim 1 in which the oscillation circuit comprises a tuning circuit free of any coils and condensers.
4. The quartz resonator of claim 3 in which the resonator is driven in third overtone.
5. The quartz resonator of claim 1 in which the impedance of the resonator has been determined by trimming the outer periphery thereof at one point on the circumference.
6. In a negative resistance oscillation circuit operable in a plurality of oscillation modes: a planar type thickness shear mode AT-cut quartz resonator having a diameter and a thickness, the ratio between the diameter and the thickness of said resonator being so designed as to obtain more stable oscillation in the third overtone mode than in other oscillation modes.
7. The quartz resonator of claim 6 in which the proportion between the diameter and the thickness of the resonator is greater than 10 and less than 24.
8. The quartz resonator of claim 6 in which the oscillation circuit comprises a tuning circuit free of any coils and condensers.
9. The quartz resonator of claim 6 in which the impedance of the resonator has been determined by trimming the outer periphery thereof at one point on the circumference.
10. The quartz resonator of claim 6 in which the difference between the impedance of the resonator and the negative resistance of the oscillation circuit is greater in the third overton
US06/885,931 1985-07-15 1986-07-15 Planar type thickness shear mode quartz oscillator Expired - Lifetime US4710731A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP60-155734 1985-07-15
JP60155734A JPS6216611A (en) 1985-07-15 1985-07-15 Plate-shaped thickness-shear crystal resonator

Publications (1)

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US4710731A true US4710731A (en) 1987-12-01

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US06/885,931 Expired - Lifetime US4710731A (en) 1985-07-15 1986-07-15 Planar type thickness shear mode quartz oscillator

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US (1) US4710731A (en)
JP (1) JPS6216611A (en)
CH (1) CH669074A5 (en)
DE (1) DE3623840A1 (en)
FR (1) FR2584866B1 (en)
GB (1) GB2177867B (en)
HK (1) HK29290A (en)
SG (1) SG55089G (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5113153A (en) * 1991-05-20 1992-05-12 International Business Machines Corporation High-frequency monolithic oscillator structure for third-overtone crystals
US20070100666A1 (en) * 2002-08-22 2007-05-03 Stivoric John M Devices and systems for contextual and physiological-based detection, monitoring, reporting, entertainment, and control of other devices
CN103018561A (en) * 2012-11-30 2013-04-03 上海斐讯数据通信技术有限公司 Detection circuit and detection method of negative impedance of chip
US10931284B2 (en) 2019-05-07 2021-02-23 Fox Enterprises, Inc. Resonators and devices with pixel based electrodes operating across a gap
US11005446B2 (en) 2019-05-07 2021-05-11 Fox Enterprises, Inc. Resonators and devices with a pixel electrode operating across a gap

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0640612B2 (en) * 1986-03-31 1994-05-25 朝日電波株式会社 Piezoelectric vibrator

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4112323A (en) * 1976-01-29 1978-09-05 Kabushiki Kaisha Daini Seikosha Circular flexural mode piezoelectric vibrator with integral support arms
JPS5675718A (en) * 1979-11-22 1981-06-23 Seiko Instr & Electronics Ltd Quartz oscillator
JPS58165412A (en) * 1982-03-26 1983-09-30 Fujitsu Ltd Crystal oscillator

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1244250B (en) * 1959-04-09 1967-07-13 Tokujiro Ando Crystal oscillator in the form of a convex, preferably biconvex lens
GB1467718A (en) * 1974-06-25 1977-03-23 Gen Electric Co Ltd Piezoelectric resonators
DE2641571B1 (en) * 1976-09-15 1977-06-08 Siemens Ag THICK SHEAR VIBRATORS USED AS OBSERVE QUARTZ
DE2752734B1 (en) * 1977-11-25 1979-04-26 Siemens Ag Thickness shear transducer used as overtone resonator
JPS55133120A (en) * 1979-04-03 1980-10-16 Seiko Instr & Electronics Ltd Thickness-slip-bending quartz oscillator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4112323A (en) * 1976-01-29 1978-09-05 Kabushiki Kaisha Daini Seikosha Circular flexural mode piezoelectric vibrator with integral support arms
JPS5675718A (en) * 1979-11-22 1981-06-23 Seiko Instr & Electronics Ltd Quartz oscillator
JPS58165412A (en) * 1982-03-26 1983-09-30 Fujitsu Ltd Crystal oscillator

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5113153A (en) * 1991-05-20 1992-05-12 International Business Machines Corporation High-frequency monolithic oscillator structure for third-overtone crystals
US20070100666A1 (en) * 2002-08-22 2007-05-03 Stivoric John M Devices and systems for contextual and physiological-based detection, monitoring, reporting, entertainment, and control of other devices
CN103018561A (en) * 2012-11-30 2013-04-03 上海斐讯数据通信技术有限公司 Detection circuit and detection method of negative impedance of chip
US10931284B2 (en) 2019-05-07 2021-02-23 Fox Enterprises, Inc. Resonators and devices with pixel based electrodes operating across a gap
US11005446B2 (en) 2019-05-07 2021-05-11 Fox Enterprises, Inc. Resonators and devices with a pixel electrode operating across a gap

Also Published As

Publication number Publication date
FR2584866B1 (en) 1991-02-22
CH669074A5 (en) 1989-02-15
HK29290A (en) 1990-04-27
GB2177867A (en) 1987-01-28
SG55089G (en) 1989-12-08
FR2584866A1 (en) 1987-01-16
JPS6216611A (en) 1987-01-24
GB2177867B (en) 1988-12-21
DE3623840A1 (en) 1987-01-15
GB8617082D0 (en) 1986-08-20

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